All Cisco Wireless LAN Controllers running version 4.2 of the network giant's software are affected by a pair of denial of service flaws. A third DoS flaw affects software versions 4.1 and later.

The denial of service bugs include a flaw in the handling of Web authentication, which can cause an affected device to reload, and a separate flaw (that also affects version 4.1 of the software) that means vulnerable kit can freeze up on receipt of malformed data packets.

The same set of potential problems affects Cisco Catalyst 6500 Series/7600 Series Wireless Services Module and Cisco Catalyst 3750 Series Integrated Wireless LAN Controllers but not the equivalent wireless modules on Cisco 2800 and 3800 series Integrated Services Routers. Cisco 2000 and 2100 Series Wireless LAN Controllers are also unaffected by the vulnerability.

The denial of service problem is not the only issue to consider. Version 4.2.173.0 of Cisco's Wireless LAN controller software is affected by a privilege escalation vulnerability. The security bug creates a means for an ordinary user to gain full administrative rights.

"Successful exploitation of the denial of service vulnerabilities may cause the affected device to hang or reload," a security advisory from Cisco explains. "Repeated exploitation could result in a sustained DoS condition. The privilege escalation vulnerability may allow an authenticated user to obtain full administrative rights on the affected system."

Cisco said it discovered the flaws via customer support cases and internal testing. There is no evidence to suggest that the flaws have been used by hackers. However, especially in the absence of a suitable workaround, patching affected systems sooner rather than later makes sense. ®